U.S. patent application number 13/294686 was filed with the patent office on 2013-05-16 for system and method for installing a fastener rod.
This patent application is currently assigned to BELL HELICOPTER TEXTRON INC.. The applicant listed for this patent is Ryan T. Ehinger, Wayland Hill, Doug Mueller. Invention is credited to Ryan T. Ehinger, Wayland Hill, Doug Mueller.
Application Number | 20130117997 13/294686 |
Document ID | / |
Family ID | 45400987 |
Filed Date | 2013-05-16 |
United States Patent
Application |
20130117997 |
Kind Code |
A1 |
Ehinger; Ryan T. ; et
al. |
May 16, 2013 |
System and Method for Installing a Fastener Rod
Abstract
A system and method for installing a fastener rod is provided.
In one embodiment a fastener rod starter apparatus is provided and
may include a first end for engaging a fastener rod, a second end
for insertion into an insertion hole, and an elongated body of
closed cell foam having sufficiently low density and high
compressibility to displace fluid in the insertion hole and be
compressed to allow installation of the fastener rod into the
insertion hole. A method for installing a fastener rod may include
lubricating an insertion hole with a fluid and inserting a starter
element into the insertion hole. The starter element may have
sufficiently low density and high compressibility to displace the
fluid in the insertion hole and be compressed by the fastener rod
inserted into the insertion hole.
Inventors: |
Ehinger; Ryan T.; (Irving,
TX) ; Hill; Wayland; (Keller, TX) ; Mueller;
Doug; (Coppell, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ehinger; Ryan T.
Hill; Wayland
Mueller; Doug |
Irving
Keller
Coppell |
TX
TX
TX |
US
US
US |
|
|
Assignee: |
BELL HELICOPTER TEXTRON
INC.
Fort Worth
TX
|
Family ID: |
45400987 |
Appl. No.: |
13/294686 |
Filed: |
November 11, 2011 |
Current U.S.
Class: |
29/525.11 ;
15/104.001; 411/378 |
Current CPC
Class: |
Y10T 29/49963 20150115;
F16B 4/004 20130101 |
Class at
Publication: |
29/525.11 ;
411/378; 15/104.001 |
International
Class: |
F16B 35/00 20060101
F16B035/00; B23P 11/00 20060101 B23P011/00; A47L 13/00 20060101
A47L013/00 |
Claims
1. A fastener rod starter apparatus, comprising: a first end for
engaging a fastener rod; a second end for insertion into an
insertion hole; and an elongated body of closed cell foam having
sufficiently low density and high compressibility to displace fluid
in the insertion hole and be compressed to allow installation of
the fastener rod into the insertion hole.
2. The apparatus of claim 1, wherein the elongated body is a
substantially cylindrical body.
3. The apparatus of claim 1, wherein the closed cell foam is closed
cell polystyrene foam.
4. The apparatus of claim 1, wherein the closed cell foam is closed
cell extruded polystyrene foam.
5. The apparatus of claim 1, wherein the second end is adapted to
mate with a feature of the insertion hole.
6. The apparatus of claim 1, wherein the second end is conical.
7. The apparatus of claim 1, wherein the fastener rod is bonded to
the first end.
8. The apparatus of claim 1, wherein the fastener rod is a threaded
fastener rod.
9. The apparatus of claim 1, wherein the fastener rod is a threaded
fastener rod bonded to the first end.
10. The apparatus of claim 1, wherein the elongated body comprises
channels between the first end and the second end.
11. The apparatus of claim 1, wherein the elongated body is sized
to provide a clearance space between the elongated body and the
insertion hole.
12. The apparatus of claim 1, wherein: the elongated body is a
substantially cylindrical body; the closed cell foam is closed cell
extruded polystyrene foam; the fastener rod is bonded to the first
end; and the second end is conical.
13. A fastener rod assembly, comprising: a fastener rod; and a
closed cell foam starter insert having a first end bonded to the
fastener rod.
14. The assembly of claim 13, wherein the starter insert comprises
a substantially cylindrical body.
15. The assembly of claim 13, wherein the closed cell foam is
closed cell polystyrene foam.
16. The assembly of claim 13, wherein the closed cell foam is
closed cell extruded polystyrene foam.
17. The assembly of claim 13, wherein the second end is adapted to
mate with a feature of an insertion hole.
18. The assembly of claim 13, wherein the fastener rod is a
threaded fastener rod.
19. The assembly of claim 13, wherein the fastener rod is a dowel
rod.
20. A method for installing a fastener rod, comprising: lubricating
an insertion hole with a fluid; inserting a starter element into
the insertion hole, wherein the starter element comprises a closed
cell foam having sufficiently low density and high compressibility
to displace the fluid in the insertion hole and be compressed to
allow installation of the fastener rod into the insertion hole; and
inserting the fastener rod into the insertion hole onto the starter
element, thereby displacing the fluid in the insertion hole and
compressing the starter element.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] This disclosure relates in general to the field of
fasteners, and more particularly to a system and method for
installing a fastener rod installation.
[0003] 2. Description of Related Art
[0004] Fastener rods, such as dowel pins and threaded studs, can be
machined to tight tolerances and are frequently used as fasteners
for mechanical components that require such tolerances, such as
gear casings, engines, and transmissions in rotorcraft drive
systems.
[0005] Many close tolerance applications demand an interference fit
or transition fit between a fastener rod and a corresponding
insertion hole. For metal parts in particular, the friction that
holds the parts together is often greatly increased by compression
of one part against the other, which relies on the tensile and
compressive strengths of the materials the parts are made from.
[0006] A liquid primer or oil is often desirable to facilitate a
satisfactory fit or reduce corrosion at the interface of the mating
components, but the liquid may be highly incompressible and can
result in cracked cases due to pressurization or inaccurate install
torque when compressed. Systems and methods for remedying this
problem can be costly and can result in many scrapped parts.
[0007] Thus, the design of a safe, cost-effective system and method
for installing fastener rods continues to present significant
challenges to engineers and manufacturers.
[0008] Although great strides have been made in head coverings,
considerable shortcomings remain.
DESCRIPTION OF THE DRAWINGS
[0009] The novel features believed characteristic of the
application are set forth in the appended claims. However, the
application itself, as well as a preferred mode of use, and further
objectives and advantages thereof, will best be understood by
reference to the following detailed description when read in
conjunction with the accompanying drawings, wherein:
[0010] FIGS. 1A-1C are simplified block diagrams of one embodiment
of a system and method for installing a fastener rod into an
insertion hole according to this specification; and
[0011] FIGS. 2A-2C are simplified schematic diagrams that
illustrate additional details that may be associated with example
embodiments of a rod starter according to this specification.
[0012] While the system and method of the present application is
susceptible to various modifications and alternative forms,
specific embodiments thereof have been shown by way of example in
the drawings and are herein described in detail. It should be
understood, however, that the description herein of specific
embodiments is not intended to limit the application to the
particular embodiment disclosed, but on the contrary, the intention
is to cover all modifications, equivalents, and alternatives
falling within the spirit and scope of the process of the present
application as defined by the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] Illustrative embodiments of the novel system are described
below. In the interest of clarity, not all features of such
embodiments may be described. It should be appreciated that in the
development of any such system, numerous implementation-specific
decisions can be made to achieve specific goals, such as compliance
with system-related and business-related constraints, which will
vary from one implementation to another. Moreover, it should be
appreciated that such decisions might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure.
[0014] Reference may be made to the spatial relationships between
various components and to the spatial orientation of various
aspects of components as the system is depicted in the attached
drawings. However, as should be recognized by those skilled in the
art, the elements, members, components, etc. described herein may
be positioned in any desired orientation. Thus, the use of terms
such as "above," "below," "upper," "lower," or other like terms to
describe a spatial relationship between various components or to
describe the spatial orientation of aspects of such components
should be understood to describe a relative relationship between
the components or a spatial orientation of aspects of such
components, respectively, as the example embodiments described
herein may be oriented in any desired direction.
[0015] For purposes of illustrating the techniques of a system and
method for fastener rod installation with an interference fit in
example embodiments, it is important to understand the principles
and challenges within a given environment. The following
foundational information is offered for purposes of explanation
only and, accordingly, should not be construed in any way to limit
the broad scope of the system, methods, and potential applications
described herein.
[0016] The term "fastener" refers generally to a broad class of
devices that mechanically join or locate two components together,
while the term "fastener rod" refers generally to a subset of
solid, cylindrical fasteners. Fastener rods may include threaded
rods (e.g., a stud) and unthreaded rods (e.g., a dowel, dowel rod,
dowel pin, etc.). Typical drilling and milling operations, as well
as manufacturing practices for bolt threads, can introduce
mechanical play proportional to the size of the fasteners. However,
many types of fastener rods can be machined to tight tolerances,
which typically result in significantly less play. Thus, fastener
rods can often be used for precise location and mating alignment in
machine assembly. In particular, engineers often use dowel holes or
stud bosses as reference points to control position variations and
to attain repeatable assembly quality. Without such reference
points for alignment (e.g., components are mated by bolts only),
there can be significant variation, or "play", in component
alignment.
[0017] Many engineering applications demand a binding fit between a
fastener rod and the components that it joins. For example, an
interference fit, also known as a press fit or friction fit, can be
achieved by friction after components are mated, rather than by
other means of fastening. For metal components in particular, the
friction that holds the components together can be greatly
increased by compression of one component against the other, which
relies on the tensile and compressive strengths and stiffness of
the materials the components are made from. A transition fit may
also bind two components together, but is not so tight that it
prevents disassembly.
[0018] A binding fit between a fastener rod and a component can
generally be achieved by shaping them so that one or the other (or
both) slightly deviate in size from a nominal dimension. For
example, an unthreaded rod such as a dowel rod may be machined
slightly larger than the nominal dimension for an interference fit.
Additionally or alternatively, an insertion hole in a component may
be reamed so that it is slightly less than the nominal dimension.
If the dowel rod is then pressed into the hole, the dowel rod
interferes with the component's occupation of space. The desired
result is that they elastically deform slightly, and the interface
between them is one of extremely high friction so that even large
amounts of torque cannot turn one of them relative to the other. An
interference fit may also be used for a threaded rod, such as a
stud, with overlapping external and internal threads. For example,
an interference fit stud can be used if the stud needs to be
restrained in its tapped hole against loosening in service or when
a nut is removed.
[0019] A primer is often desirable to facilitate an interference
fit and/or reduce corrosion in the interface, but the primer may be
a highly incompressible fluid and can result in cracked cases or
inaccurate install torque when compressed. For example, lubricant
in a 5/16'' stud boss can create pressure in excess of 30 ksi after
stud installation. Systems and methods for remedying this problem
can be costly and can result in many scrapped parts.
[0020] For example, a drilled vent hole in a housing can allow
fluid (i.e., liquid and/or gas) to escape upon installation, but
requires additional machining operations that increases component
cost and can result in significant waste. A drilled fastener rod
can also allow fluid to escape upon rod installation, but may only
be practical for short rods not exposed to the atmosphere where
there is a risk of corrosion on the rod interior. Moreover, the
cost for such non-standard parts also increases component cost. A
keyway or slotted vent may also be cut in the side of a rod, but
such a feature can weaken the rod and increase the potential for
corrosion. Leaving a sufficient air gap at the bottom of an
insertion hole can also reduce pressure, but liquid primer can also
build up in the hole if not sufficiently cleaned prior to
installation, which can be very susceptible to human error.
[0021] In accordance with embodiments disclosed herein, a rod
starter insert can substantially reduce or eliminate many of these
shortcomings (and others) without modifying parts or significantly
increasing cost. In one embodiment, the rod starter insert is a
closed-cell foam having a low density and high compressibility,
which can be placed in an insertion hole prior to installation of a
fastener rod. Thus, the insert can displace fluid (e.g., primer
and/or oil) in the hole, but may be significantly compressed during
installation such that the fastener rod can be fully installed
without over-pressurizing the hole.
[0022] FIG. 1A is a simplified block diagram of one embodiment of a
system for installing a fastener rod into an insertion hole. In
this particular embodiment, the fastener rod is a stud (i.e., a
threaded rod) 10 and the insertion hole is a stud boss 12. Stud 10
and stud boss 12 may be lubricated with a fluid, such as primer and
oil 14. A rod starter 16 may be placed over and longitudinally
aligned with stud boss 12. FIG. 1B is a simplified block diagram of
the system of FIG. 1A in which rod starter 16 is inserted into stud
boss 12 to displace primer and oil 14 from stud boss 12. FIG. 1C is
a simplified block diagram of the system in FIG. 1A in which stud
10 is installed into stud boss 12. Installation of stud 10 into
stud boss 12 compresses rod starter 16. The volume reduction of rod
starter 16 may vary considerably based on design requirements, but
assuming a 90% reduction in volume, the air pressure in stud boss
12 should only increase by approximately 140 psi. Preferably, stud
boss 12 provides sufficient room to accommodate residual fluid,
compressed air, and rod starter 16.
[0023] FIGS. 2A-2C are simplified schematic diagrams that
illustrate additional details that may be associated with certain
example embodiments of a rod starter. In general, a rod starter may
be molded, fabricated, or cut to conform to the shape of any
insertion hole, but is preferably a cylindrical block element. In
FIG. 2A, for example, a rod starter 20a has two opposing ends
21a-22a and an elongated body with a cylindrical wall 23a. Rod
starter 20a can be installed in a corresponding insertion hole
without regard to orientation of ends 21a-22a. FIG. 2B, however,
illustrates a rod starter 20b having a flat end 21b and a distal
end 22b adapted to conform to a feature in an insertion hole. For
example, distal end 22b may be substantially conical to conform to
a drill point in an insertion hole, for example. Thus, rod starter
20b may displace more fluid than rod starter 20a when tapered end
22b is properly oriented and installed in the bottom of a
corresponding insertion hole. FIG. 2C illustrates yet another
embodiment of a rod starter 20c bonded to a fastener rod 23c. In
this particular example, rod starter 20c has a tapered end 22c
similar to tapered end 22b, but may alternatively have a flat
surface similar to surface 22a. In more particular embodiments, a
rod starter may also be sized such that fluid can escape an
insertion hole through channels or grooves in the side of the
starter rod, or between clearance space between the body of the
starter and walls of an insertion hole.
[0024] A rod starter element may be constructed from any closed
cell foam having sufficiently low density and high compressibility
that it can displace fluid in an insertion hole and be compressed
to allow full installation of a fastener rod without
over-pressurizing the hole. For example, a rod starter element may
be constructed from rigid polystyrene foam, including expanded or
extruded polystyrene foam (e.g., STYROFOAM).
[0025] The system and apparatus described herein provides
significant advantages, some of which have already been mentioned.
For example, a rod starter as described herein may be a passive
device not requiring changes to components or fastener rods. It can
be made of highly compressible and rigid closed cell material that
can retain its shape to displace fluid yet may be readily
compressed during rod installation. Moreover, a rod starter can be
sized such that after insertion, fluid in the hole can be
compressed to the maximum amount required by a given design with
pressurization of the hole well below design limits. A rod starter
may be shaped like a cylinder that can be installed in any
direction, or like a pointed cylinder that can be installed one way
and displace more fluid. A rod starter can also be installed freely
prior to rod installation or may be bonded to the rod to further
facilitate proper installation.
[0026] Certain example embodiments have been shown in the drawings
and described above, but variations in these embodiments will be
apparent to those skilled in the art. The principles disclosed
herein are readily applicable to a variety of industries and
mechanical components needing close tolerance fasteners, including
rotorcraft drive systems. The preceding description is for
illustration purposes only, and the claims below should not be
construed as limited to the specific embodiments shown and
described.
* * * * *